Stent including an expandable member

ABSTRACT

Example medical stents are disclosed. An example stent includes a tubular framework including an inner surface, an outer surface and a lumen extending therethrough. Additionally, the stent includes a tissue ingrowth scaffold extending along a portion of the outer surface of the tubular framework, wherein the tissue ingrowth scaffold is spaced radially away from the outer surface of the tubular framework to define an expansion cavity therebetween and wherein the tissue ingrowth scaffold permits tissue ingrowth along a portion thereof. Further, the stent includes an expandable member positioned within at least a portion of the expansion cavity.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. § 119 to U.S.Provisional Application Serial No. 62/598,747, filed Dec. 14, 2017, theentirety of which is incorporated herein by reference.

TECHNICAL FIELD

The present disclosure pertains to medical devices, methods formanufacturing medical devices, and the use thereof. More particularly,the present disclosure pertains to stents designed to be removed fromthe body and methods for manufacturing and using such stents.

BACKGROUND

A wide variety of intracorporeal medical devices have been developed formedical use, for example, intravascular use. In some instances themedical devices (e.g., self-expanding stents) are placed in a body lumen(e.g., esophagus, gastrointestinal tract, etc.) for the treatment of avariety of disorders. However, in some instances the compressible andflexible properties that assist in stent positioning may also result ina stent that has a tendency to migrate from its originally deployedposition. For example, stents that are designed to be positioned in theesophageal or gastrointestinal tract may have a tendency to migrate dueto peristalsis (i.e., the involuntary constriction and relaxation of themuscles of the esophagus, intestine, and colon which push the contentsof the canal therethrough). Additionally, the generally moist andinherently lubricious environment of the esophagus, intestine, colon,etc. further contributes to a stent's tendency to migrate when deployedtherein. One method to reduce stent migration may include exposing bareportions of the stent to the tissue of the body lumen. The stentscaffold may provide a structure that promotes tissue ingrowth into theinterstices or openings thereof (e.g., the stent structure may promote ahyperplastic response). The tissue ingrowth may anchor the stent inplace and reduce the risk of stent migration.

Additionally, while it is important to design stents that reduce thedegree to which a stent migrates within a body lumen, it is alsoimportant to design stents that may be easily removed and/orre-positioned from the body lumen post-deployment. Stents including bareportions (i.e., uncovered portions) designed to promote tissue ingrowth(e.g., to reduce stent migration as described above) may consequently bemore difficult to remove once the tissue has anchored the stent in thebody lumen.

BRIEF SUMMARY

This disclosure provides design, material, manufacturing method, and usealternatives for medical devices. An example stent includes a tubularframework including an inner surface, an outer surface and a lumenextending therethrough. Additionally, the stent includes a tissueingrowth scaffold extending along a portion of the outer surface of thetubular framework, wherein the tissue ingrowth scaffold is spacedradially away from the outer surface of the tubular framework to definean expansion cavity therebetween and wherein the tissue ingrowthscaffold permits tissue ingrowth along a portion thereof. Further, thestent includes an expandable member positioned within at least a portionof the expansion cavity.

Alternatively or additionally to any of the embodiments above, whereinthe expandable member is configured to expand radially outward toward aninner surface of the tissue ingrowth scaffold.

Alternatively or additionally to any of the embodiments above, whereinthe expandable member is configured to exert a radially outwardexpansion force on the tissue ingrowth scaffold such that the outersurface of the tissue ingrowth scaffold shifts radially outward from afirst positon to a second position.

Alternatively or additionally to any of the embodiments above, whereinthe expandable member is configured to exert a radially outward forceupon the tissue ingrowth scaffold causing tissue ingrowth to recede.

Alternatively or additionally to any of the embodiments above, whereinthe expandable member extends circumferentially around the outer surfaceof the tubular framework.

Alternatively or additionally to any of the embodiments above, whereinthe expandable member includes an expandable sleeve and an expandablematerial positioned within a void of the expandable sleeve.

Alternatively or additionally to any of the embodiments above, whereinthe expandable material is configured to expand when exposed to anexternal stimuli.

Alternatively or additionally to any of the embodiments above, whereinthe external stimuli is a liquid.

Alternatively or additionally to any of the embodiments above, whereinthe expandable sleeve is configured to dissolve over a time period toexpose the expandable material.

Alternatively or additionally to any of the embodiments above, whereinthe expandable member includes an inflatable sleeve, and wherein theinflatable sleeve is configured to shift from a first unexpandedconfiguration to a second expanded configuration when inflated.

Alternatively or additionally to any of the embodiments above, whereinthe tissue ingrowth scaffold extends along the outer surface of thetubular framework from an end of the tubular framework, and wherein thescaffold folds back on the tubular framework to form the expansioncavity.

Alternatively or additionally to any of the embodiments above, furthercomprising a covering disposed along a portion of the tubular framework,wherein the covering is configured to prevent tissue from growing intothe lumen of the tubular framework.

Alternatively or additionally to any of the embodiments above, whereinthe tissue ingrowth scaffold includes a wire mesh having one or moreapertures configured to permit tissue ingrowth therethrough.

Another example stent includes a tubular framework having a first endand a second end opposite the first end. The tubular framework includesan inner surface, an outer surface and a lumen extending therethrough. Atissue ingrowth scaffold extends along a portion of the outer surface ofthe tubular framework. The tissue ingrowth scaffold is spaced radiallyaway from the outer surface of the tubular framework to define anexpansion cavity therebetween. The tissue ingrowth scaffold permitstissue ingrowth along a portion thereof. A covering is disposed alongthe tubular framework. The covering is configured to prevent tissue fromgrowing into the lumen of the tubular framework between the first endand the second end. An expandable member is positioned within at least aportion of the expansion cavity. The expandable member is configured toradially expand from a first nominal state to an expanded state whensubjected to an external stimuli. The expandable member is configured toexert a radially outward force upon the tissue ingrowth scaffold in theexpanded state to cause tissue ingrowth within the tissue ingrowthscaffold to recede.

Alternatively or additionally to any of the embodiments above, whereinthe expandable member is configured to expand radially outward toward aninner surface of the tissue ingrowth scaffold.

Alternatively or additionally to any of the embodiments above, whereinthe expandable member extends circumferentially around the outer surfaceof the tubular framework.

Alternatively or additionally to any of the embodiments above, whereinthe expandable member includes an expandable sleeve and an expandablematerial positioned within a void of the expandable sleeve.

Alternatively or additionally to any of the embodiments above, whereinthe external stimuli is a liquid.

Alternatively or additionally to any of the embodiments above, whereinthe expandable sleeve is configured to dissolve over a time period toexpose the expandable material.

Alternatively or additionally to any of the embodiments above, whereinthe tissue ingrowth scaffold includes a wire mesh having one or moreapertures configured to permit tissue ingrowth therethrough.

An example method of treating a body lumen includes activating anexpandable member positioned between a tissue ingrowth scaffold and atubular framework of a pre-deployed stent having tissue ingrown into thetissue ingrowth scaffold. Activating the expandable member causes theexpandable member to shift radially from a first unexpandedconfiguration to a second expanded configuration. Shifting theexpandable member from a first unexpanded configuration to a secondexpanded configuration includes exerting a radially outward force uponthe tissue which has grown into the tissue ingrowth scaffold. Exerting aradially outward force upon the tissue which has grown into the tissueingrowth scaffold causes the tissue to recede.

The above summary of some embodiments is not intended to describe eachdisclosed embodiment or every implementation of the present disclosure.The Figures and Detailed Description, which follow, more particularlyexemplify these embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure may be more completely understood in consideration of thefollowing detailed description in connection with the accompanyingdrawings, in which:

FIG. 1 is a side view of an example stent;

FIG. 2 is a cross-sectional view of the stent shown in FIG. 1;

FIG. 3 is a cross-sectional view along line 3-3 of the stent shown inFIG. 2;

FIG. 4 is a cross-sectional view of another example stent;

FIG. 5 illustrates an example stent positioned within a body lumen;

FIG. 6 illustrates a portion of the example stent shown in FIG. 5positioned within a body lumen;

FIG. 7 illustrates a portion of the example stent shown in FIG. 5positioned within a body lumen;

FIG. 8 illustrates another example stent;

FIG. 9 illustrates a portion of the example stent shown in FIG. 5positioned within a body lumen;

FIG. 10 illustrates the example stent shown in FIG. 5 being removed froma body lumen;

FIG. 11 illustrates another example stent;

FIG. 12 illustrates a portion of the example stent shown in FIG. 11positioned within a body lumen;

FIG. 13 illustrates a portion of the example stent shown in FIG. 11positioned within a body lumen;

FIG. 14 illustrates a portion of the example stent shown in FIG. 11including expansion of an expandable material.

While the disclosure is amenable to various modifications andalternative forms, specifics thereof have been shown by way of examplein the drawings and will be described in detail. It should beunderstood, however, that the intention is not to limit the disclosureto the particular embodiments described. On the contrary, the intentionis to cover all modifications, equivalents, and alternatives fallingwithin the spirit and scope of the disclosure.

DETAILED DESCRIPTION

For the following defined terms, these definitions shall be applied,unless a different definition is given in the claims or elsewhere inthis specification.

All numeric values are herein assumed to be modified by the term“about”, whether or not explicitly indicated. The term “about” generallyrefers to a range of numbers that one of skill in the art would considerequivalent to the recited value (e.g., having the same function orresult). In many instances, the terms “about” may include numbers thatare rounded to the nearest significant figure.

The recitation of numerical ranges by endpoints includes all numberswithin that range (e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and5).

As used in this specification and the appended claims, the singularforms “a”, “an”, and “the” include plural referents unless the contentclearly dictates otherwise. As used in this specification and theappended claims, the term “or” is generally employed in its senseincluding “and/or” unless the content clearly dictates otherwise.

It is noted that references in the specification to “an embodiment”,“some embodiments”, “other embodiments”, etc., indicate that theembodiment described may include one or more particular features,structures, and/or characteristics. However, such recitations do notnecessarily mean that all embodiments include the particular features,structures, and/or characteristics. Additionally, when particularfeatures, structures, and/or characteristics are described in connectionwith one embodiment, it should be understood that such features,structures, and/or characteristics may also be used connection withother embodiments whether or not explicitly described unless clearlystated to the contrary.

The following detailed description should be read with reference to thedrawings in which similar elements in different drawings are numberedthe same. The drawings, which are not necessarily to scale, depictillustrative embodiments and are not intended to limit the scope of thedisclosure.

As discussed above, in some instances an implantable medical device maybe designed to provide a pathway for digested material, blood, or otherfluid to flow therethrough following a medical procedure. These medicaldevices may include radially or self-expanding stents which may beimplanted transluminally via an endoscope or similar medical device.Additionally, some stents may be implanted in a variety of body lumenssuch as the esophageal tract, the gastrointestinal tract (including theintestine, stomach and the colon), tracheobronchial tract, urinarytract, biliary tract, vascular system, etc.

In some instances it may be desirable to design a stent which includessufficient radial strength to maintain its positon within a body lumenwhile also having the ability to function as a passageway for food orother digested material to flow therethrough. However, in some stents,the compressible and flexible properties that assist in stentpositioning may also result in a stent that has a tendency to migratefrom its originally deployed position. For example, stents that aredesigned to be positioned in the esophageal or gastrointestinal tractmay have a tendency to migrate due to peristalsis (i.e., the involuntaryconstriction and relaxation of the muscles of the esophagus, intestine,and colon which push the contents of the canal therethrough).Additionally, the generally moist and inherently lubricious environmentof the esophagus, intestine, colon, etc. further contributes to astent's tendency to migrate when deployed therein. One method to reducestent migration may include exposing bare metal portions of the stent tothe tissue of the body lumen. The stent scaffold may provide a structurethat promotes tissue ingrowth (e.g., a hyperplastic response) into theinterstices or openings thereof. The tissue ingrowth may anchor thestent in place and reduce the risk of stent migration.

Additionally, while it is important to design stents that reduce thedegree to which a stent migrates within a body lumen, it is alsoimportant to design stents that may be easily removed and/orre-positioned from the body lumen post-deployment. Stents including bareportions (i.e., uncovered portions) designed to promote tissue ingrowth(e.g., to reduce stent migration as described above) may consequently bemore difficult to remove once the tissue has anchored the stent in thebody lumen. Thus, it may be desirable to provide a stent that permitstissue ingrowth to inhibit stent migration, while also permitting lesstraumatic selective removability of the stent. One method to reduce theforce and/or tissue trauma necessary to remove a stent from a bodylumen, as disclosed herein, may include expanding an expandable memberradially outward against the ingrown tissue. The radial expansion of theexpandable member may cause the tissue ingrowth to recede, therebyreducing the force and/or tissue trauma necessary to remove the stentfrom the wall of the body lumen. Examples of stents including a radiallyexpandable member are disclosed herein.

FIG. 1 shows an example stent 10. The stent 10 may include a tubularframework 12 having a first end 16, which may extend to the first end ofthe stent 10, a second end 18, which may extend to the second end of thestent 10, and a lumen extending therethrough. When positioned in a bodylumen (e.g., esophagus) the first or proximal end 16 may be defined asthe end of stent 10 closest to a patient's mouth and the second ordistal end 18 may be defined as the end of the stent 10 closest to apatient's stomach.

The tubular framework 12 may be configured to provide the supportstructure for the stent 10. The tubular framework 12 may be formed ofone or more stent filaments 14, or a plurality of stent filaments 14.The filaments 14 may extend longitudinally along the stent 10. In someinstances, the filaments 14 may extend longitudinally along the stent 10in a helical fashion. While FIG. 1 shows the filaments 14 extendingalong the entire length of the stent 10 between the first end 16 and thesecond end 18 of the stent 10, in other examples, the filaments 14 mayextend only along a portion of the length of stent 10. Further, FIG. 1shows that stent 10 may include a retrieval suture 62 extendingcircumferentially around the first end 16 of the stent 10. Retrievalsuture 62 may be looped through the filaments 14, for example.

Additionally, FIG. 1 shows the example stent 10 including a first flaredend region 20 proximate the first end 16 and/or a second flared region22 proximate the second end 18 of the stent 10. In some instances, thefirst flared region 20 and the second flared region 22 may be defined asan increase in the outer diameter, the inner diameter or both the innerand outer diameter along one or both of the first end 16 and/or thesecond end 18 of the stent 10 relative to an outer diameter of a medialregion 24 of the stent 10 therebetween. Further, FIG. 1 illustrates thestent 10 including a medial region 24 having a cylindrical configurationpositioned between the first flared region 20 and the second flaredregion 22.

However, it is contemplated that while FIG. 1 shows the stent 10including both a first flared region 20 and a second flared region 22,the stent 10 may only include one flared region. For example, it iscontemplated that the stent 10 may include only the first flared region20 or the second flared region 22, or the stent 10 may have a constantdiameter along its entire length. It is further contemplated that all ora portion of the first flared region 20 and/or the second flared region22 may flare outwardly (e.g., away from the central, longitudinal axisof stent 10). Alternatively, it is further contemplated that all or aportion of the first flared region 20 and/or the second flared region 22may flare inwardly (e.g., toward the central, longitudinal axis of stent10).

In some instances, the stent 10 may be a self-expanding stent.Self-expanding stent examples may include stents having one or moreinterwoven filaments 14 to form the tubular framework 12, havingopenings defined between adjacent filaments 14. For example, the stentfilaments 14 may be wires braided, knitted or otherwise interwoven toform the tubular framework 12. Openings or interstices through the wallof the tubular framework 12 may be defined between adjacent stentfilaments 14. Alternatively, the tubular framework 12 of the stent 10may be a monolithic structure formed from a cylindrical tubular member,such as a single, cylindrical tubular laser-cut Nitinol tubular member,in which the remaining portions of the tubular member form the stentfilaments 14 with openings defined therebetween.

The stent 10, or components thereof, (including the tubular framework 12and/or the stent filaments 14) disclosed herein may be constructed froma variety of materials. For example, the stent 10 (e.g., self-expandingor balloon expandable), or components thereof, may be constructed from ametal (e.g., Nitinol). In other instances, the stent 10 or componentsthereof may be constructed from a polymeric material (e.g., PET). In yetother instances, the stent 10, or components thereof, may be constructedfrom a combination of metallic and polymeric materials. Additionally,the stent 10, or components thereof, may include a bioabsorbable and/orbiodegradable material.

Additionally, the stent 10 may include one or more covering layers 26disposed on the tubular framework 12, such as positioned on and/oradjacent to the inner surface and/or outer surface thereof. The coveringlayer 26 may be positioned on a portion of the filaments 14 forming thetubular framework 12 and extend across openings or cells betweenadjacent filaments 14. For example, FIG. 2 shows the stent 10 includinga covering layer 26 disposed along the outer surface of the tubularframework 12. In some instances, the covering layer 26 may be anelastomeric or non-elastomeric material. For example, the covering layer26 may be a polymeric material, such as silicone, polyurethane, or thelike. Further, the covering layer 26 may span the spaces (e.g.,openings, cells, interstices) in the wall of the tubular framework 12defined between adjacent filaments 14. For example, the covering layer26 may extend along and cover the inner surface and/or outer surface ofthe tubular framework 12 such that the covering layer 26 spans one ormore of spaces (e.g., openings, cells, interstices) between thefilaments 14 in the wall of the tubular framework 12. In some instances,the covering layer 26 may extend circumferentially around the entirecircumference of the tubular framework 12 and extend the entire lengthof the tubular framework 12 from the first end 16 to the second end 18such that the covering layer 26 covers each opening or interstice of thetubular framework 12, thus forming a completely covered stent to preventtissue ingrowth into the lumen of the stent 10.

As described above, the stent 10 may have a first end 16 and a secondend 18. When positioned in a body lumen, the first end 16 may be definedas the proximal end of the stent 10 and oriented as the end of the stent10 closest to a patient's mouth and second end 18 may be defined as thedistal end of stent 10 and oriented as the end of stent 10 closest to apatient's stomach. As shown in FIG. 2, the covering layer 26 may extendalong the length of the tubular framework 12 from the first end 16 tothe second end 18. In other words, in some instances the covering layer26 may be defined as a continuous layer that extends from first end 16to second end 18 of stent 10 and fully extends across and fills cells orinterstices defined between filaments 14 of the tubular framework 12.However, in other instances covering layer 26 may extend less than theentire length of stent 10, if desired, leaving a portion of cells orinterstices defined between the filaments 14 of the tubular framework 12unfilled or open.

FIG. 1 further illustrates that in some examples, the stent 10 mayinclude a tissue ingrowth scaffold 28 extending along a portion of theouter surface of the tubular framework 12. The tissue ingrowth scaffold28 may be defined as an uncovered region (e.g., a tissueingrowth-promoting section, an anti-migration section, etc.) of thestent 10. The uncovered openings present in the tissue ingrowth scaffold28 may permit the stent 10 to be securely implanted (e.g., permit tissueingrowth) at a target site (e.g., within a body lumen). As will bedescribed in further detail below, the tissue ingrowth scaffold 28 mayinclude wires 30 that are braided, knitted or otherwise interwoventogether to form the tissue ingrowth scaffold 28. In some examples, thetissue ingrowth scaffold 28 may be free from the covering 26 describedabove. For example, the covering 26 may extend radially within thetissue ingrowth scaffold 28 but be unattached to or otherwise notobstruct tissue ingrowth into the tissue ingrowth scaffold.

FIG. 2 shows a cross-section of the example stent 10 of FIG. 1. FIG. 2illustrates that the first flared region 20 and/or the second flaredregion 22 of stent 10 may include tapered portions 32 and end portions34. While FIG. 2 shows the tapered portions 32 tapering radially outwardtoward ends of stent 10, it is contemplated that one or more of thetapered portions 32 may, alternatively, taper radially inward.

As described above, the stent 10 may include the tissue ingrowthscaffold 28 extending along an outer surface 42 of the tubular framework12, radially outward of the covering layer 26. The tissue ingrowthscaffold 28 may be located at any desired location along the tubularframework 12. For example, a first end of the tissue ingrowth scaffold28 may be coupled (e.g., attached) to the outer surface 42 of thetubular framework 12 at an end point 36 of the end portion 34 of thefirst end 16 of the stent 10. A second end of the tissue ingrowthscaffold 28 may be coupled (e.g., attached) to the outer surface 42 ofthe tubular framework 12 at a connection point 38 along the end portion34 of the first end 16 of the stent 10. Various attachment techniquesmay be utilized to attach the tissue ingrowth scaffold 28 to the tubularframework 12. For example, the tissue ingrowth scaffold 28 may beattached via welding, suturing, stitching, etc. Additionally, while FIG.2 shows the connection point 38 being positioned along the end portion34, it is contemplated that the connection point 38 may be positionedalong tapered region 32, for example.

The detailed view of FIG. 2 illustrates the tissue ingrowth scaffold 28attached at both the end point 36 and the connection point 38, asdescribed above. Further, it can be appreciated that the tissue ingrowthscaffold 28, along with the tubular framework 12, may form an expansion“cavity” 40 bounded by the outer surface 42 of the tubular framework 12and the inner surface 44 of the tissue ingrowth scaffold 28. Theexpansion cavity 40 may define a void, or space, which is bounded by theouter surface 42 of the tubular framework 12 and the inner surface 44 ofthe tissue ingrowth scaffold 28. As will be described in greater detailbelow, the tissue ingrowth scaffold 28 may extend circumferentiallyaround the outer surface 42 of the tubular framework 12. Therefore, itcan be appreciated that the expansion cavity 40 may entirely extendcircumferentially around the outer surface of the tubular framework 12of the stent 10 in some instances.

FIG. 2 further illustrates that in some examples, stent 10 may includean expansion member 46 positioned within the expansion cavity 40. Insome examples, the expansion member 46 may entirely extendcircumferentially around the outer surface 42 of the tubular framework12. As will be described in greater detail below, the expansion member46 may expand from a first unexpanded configuration to a second expandedconfiguration. In the expanded configuration, the expansion member 46may conform and fill the space defined by the expansion cavity 40. Inother examples, the expansion member 46 may expand to alter the shape ofthe expansion cavity 40 by exerting a radial outward force upon thetissue ingrowth scaffold 28.

As illustrated in the detailed view of FIG. 2, the expansion member 46may include an expandable material 50 surrounded by an outer sleeve 48in some instances. The outer sleeve 48 may be constructed from polymericmaterial which permits the sleeve 48 to stretch, expand and/or changeshape as needed. It can be appreciated that sleeve 48 may be shaped likea torus. Example materials that may be utilized to construct the sleeve48 may include silicone, Chronoflex®, UE, PVDF, PTFE or other similarmaterials. Further, as will be discussed in greater detail below, it iscontemplated that the sleeve 48 may be constructed from a biodegradablematerial in some instances. The biodegradable material may be designedto degrade over a specific time period to expose the expandable material50 within the outer sleeve 48. For example, the sleeve 48 may beconstructed from a biodegradable material that biodegrades upon exposureto magnetic waves, an electromagnetic field (EMF), electrical signals,various liquids, heat, etc. A non-limiting list of materials which maybe utilized to construct sleeve 48 are disclosed below.

A variety of different materials are contemplated for the expandablematerial 50. For example, the expandable material 50 may include asuperabsorbent material, superabsorbent polymer (e.g., superabsorbentwater absorbing crystal polymers including, but limited to crosslinkedpolyacrylic acid), superabsorbent polymer composites, electroactivepolymers and/or other similar materials. A common, beneficial propertyof these materials is that they may expand from a first volume to asecond volume when contacted by a particular media. For example, thesematerials may expand when contacted by a liquid or aqueous solution suchas water, DI water, saline, urine, blood, etc.

While FIG. 2 illustrates the tissue ingrowth scaffold 28 disposed alongthe distal portion 34 of the tubular framework 12, it is contemplatedthat the tissue ingrowth scaffold 28 may be positioned at any pointalong the outer surface 42 of the tubular framework 12. For example, thetissue ingrowth scaffold 28 may be positioned along the tapered regions32 and/or the medial region 24 of the stent 10. Further, it iscontemplated that the stent 10 may include more than one tissue ingrowthscaffold 28. For example, the stent 10 may include a combination oftubular scaffolds 28 positioned along the first flared region 20, thesecond flared region 22 and/or the medial region 24.

FIG. 3 shows a cross-sectional view of the stent 10 taken along line 3-3of FIG. 2. FIG. 3 shows tubular framework 12 extending circumferentiallyaround the longitudinal axis 60 of the stent 10. Additionally, covering26, such as a polymeric coating, is shown disposed along the tubularframework 12. Further, FIG. 3 illustrates the expandable member 46positioned between the outer surface 42 of the tubular framework 12 andthe inner surface of the tissue ingrowth scaffold 28. FIG. 3 furtherillustrates the expandable material 50 positioned within an expandablesleeve 48 of the expandable member 46.

FIG. 4 illustrates another example stent 110. Example stent 110 may besimilar in form and function to the example stent 10 described above.For example, the stent 110 may include a tubular framework 112 having acovering 126 disposed along a portion thereof. The tubular framework 112may be constructed from wires and/or filaments 114. Further, the stent110 may include a tissue ingrowth scaffold 128 extending along a portionof the outer surface of the tubular framework 112, radially outward ofthe covering 126. The tissue ingrowth scaffold 128 may include wiresand/or filaments 130 which are braided, knitted, etc. to form anexpandable scaffold designed to promote tissue to grow thereon.

Additionally, FIG. 4 further illustrates that the tissue scaffold 128may be formed from the wires and/or filaments 114 used to construct thetubular framework 112. For example, FIG. 4 shows that the tissueingrowth scaffold 128 may be formed as an extension of the wires and/orfilaments 114 of tubular framework 112 which are folded back on thetubular framework 112 and attached to the outer surface of the tubularframework 112 (at attachment point 138, for example). Thus, the tissueingrowth scaffold 128 may be constructed of wires and/or filaments 114of the tubular framework 112 folded back at the first end 116 andextending toward the second end 118 radially outward of the tubularframework 112. In other examples, the wires and/or filaments 130 used toconstruct the tissue ingrowth scaffold 128 may be different from thewires and/or filaments 114 used to construct the tubular scaffold 112,yet they may be interwoven with each other.

It can be appreciated from FIG. 4 that the tissue ingrowth scaffold 128and the tubular framework 112 may form an expansion cavity 140therebetween which is similar in form and function to the expansioncavity 40 discussed above. It can be further appreciated that the stent110 may include an expandable member 146 positioned within the expansioncavity 140. The expandable member 146 may be similar in form andfunction to the expandable member 46 discussed above.

As discussed above, stents that are designed to be positioned in a bodylumen (e.g., esophageal or gastrointestinal tract) may have a tendencyto migrate (due to peristalsis and/or the generally moist and inherentlylubricious environment of the body lumens). Therefore, one method toreduce stent migration may include exposing tissue ingrowth promotingregions, such as uncovered and/or bare metal portions of the stent tothe tissue of the body lumen. The uncovered or bare stent scaffold mayprovide a structure that promotes tissue ingrowth into the intersticesor openings thereof. The tissue ingrowth may anchor the stent in placeand reduce the risk of stent migration.

Accordingly, it can be appreciated that the portions of the stent 10discussed above which include the covering 26 which covers the stentstruts or filaments 14 may act to prevent tissue from growing into theinterstices or openings thereof, and thus prevent tissue ingrowth intothe lumen of the stent. For example, the struts or filaments 14 of theend portions 34, tapered regions 32 and medial region 24 of the stent 10which includes the covering 26 attached thereto to thereby span acrossinterstices of the tubular scaffold 12 may prevent tissue ingrowth alongtheir respective surfaces and interstices therebetween. The covering 26may prevent the tissue from growing into the lumen of stent 10.

However, it can be appreciated that tissue may be permitted to growaround, between, through, within, etc. portions of the stent 10 in whichthe covering 26 is not present. For example, it can be appreciated thattissue may be permitted to grow around, between, through, within thefilaments 30 of the tissue ingrowth scaffold 28.

FIGS. 5-6 illustrate the example stent 10 undergoing a hyperplasticresponse while FIGS. 7 and 9-10 illustrate the removal of stent 10 viaexpansion of an expandable member to free the stent 10 from the ingrowntissue anchoring the stent 10.

FIGS. 5-6 illustrate the example stent undergoing a hyperplasticresponse of tissue within an example body lumen subsequent toimplantation of the stent 10 (or any example stent embodiment describedherein) within a body lumen 52. FIG. 5 shows the stent 10 deployed inbody lumen 52. As illustrated, upon initial deployment in the body lumen52, the end portion 34 of the first flared region 20 and the end portion34 of the second flared region 22 may apply a radially outward forceupon the inner surface of the body lumen 52 as the tubular framework 12of the stent 10 expands to an expanded state in the body lumen 52. Thisradially outward force exerted on the inner surface of body lumen 52 mayprovide a temporary resistance to migration of the stent 10 within thebody lumen 52.

Additionally, FIG. 5 illustrates that the tissue ingrowth scaffold 28may contact the tissue on the inner surface of body lumen 52. Theengagement of the tissue ingrowth scaffold 28 with the tissue along theinner surface of the body lumen 52 may provide a seal that permits foodor other material to travel through the lumen of the stent 10 and,additionally, may prevent the food from traveling along the exterior ofthe stent 10 and along the inner surface of the body lumen 52.Additionally, it can be appreciated from the above discussion that thetissue ingrowth scaffold 28 may engage the tissue on the inner surfaceof the body lumen 52 circumferentially along the inner surface of thebody lumen 52.

Engagement of the tissue ingrowth scaffold 28 may stimulate the onset ofa hyperplastic response along the tissue ingrowth scaffold 28. Thehyperplastic response may result in tissue from the body lumen 52 togrow through the interstices of the tissue ingrowth scaffold 28. Forexample, FIG. 6 illustrates tissue 54 extending through the intersticesof the filaments 30 along the tissue ingrowth scaffold 28 of the stent10. As discussed above, the tissue ingrowth scaffold 28 (including thefilaments 30) may be uncovered, and therefore, may permit the radiallyinward growth of tissue through the interstices of the tissue ingrowthscaffold 28. However, the presence of the covering 26 radially inward ofthe tissue ingrowth scaffold 28 may prevent the growth of tissue throughthe tubular framework 12 into the lumen of the stent 10. FIG. 6 furtherillustrates that the tissue 54 may grow in a direction toward thetubular framework 12 (as depicted by the arrows in FIG. 6) and into thefilaments 30 of the tissue ingrowth scaffold 28. It can be appreciatedthat the growth of tissue through the interstices of the tissue ingrowthscaffold 28 may anchor the stent 10 along the body lumen 52, therebylimiting or preventing the stent 10 from being dislodged due toperistaltic or other forces acting upon it.

In some instances, it may be desirable to remove the stent 10 subsequentto the tissue in-growth through interstices of the tissue ingrowthscaffold 28. However, the tissue-ingrowth may hinder removal and/orcause undesirable trauma to the body lumen. As discussed above, FIGS. 7and 9-10 illustrate an example methodology for removing and retrievingan example stent 10 (or any other devices disclosed herein) from a bodylumen while reducing the amount of trauma to the body lumen. Examplestent 10 shown in FIGS. 7 and 9-10 may depict the stent 10 or stent 110illustrated and described above with respect to FIGS. 1-6. Further, itis contemplated that the methodology described herein with respect toFIGS. 7 and 9-10 may be used to retrieve and/or remove stent 10, stent110, stent 210 or any other devices disclosed herein.

It can be appreciated that one method to remove a stent which has beenanchored via a hyperplastic response (e.g., tissue ingrowth) may be toreverse the ingrowth of tissue. In other words, one technique to free astent that is anchored to tissue along an inner surface of a body lumen(such as stent 10, stent 110 or any other stent described herein) mayinclude pushing the tissue radially outward with sufficient force suchthat the tissue recedes back through the stent filaments, therebyfreeing the filaments from the tissue.

FIG. 7 illustrates an example first step in removing the stent 10 froman example body lumen 52 via forcing the ingrown tissue to recede backthrough the filaments 30 of the tissue ingrowth scaffold 28. Asdiscussed above, the expandable member 46 may include an expandablematerial 50 encapsulated in a sleeve member 48. In some examples, theexpandable material 50 may expand when it comes into contact with asubstance that causes (e.g. activates, stimulates, energizes, triggers,elicits, etc.) the expandable material 50 to shift from a first,unexpanded volume to a second, expanded volume greater than the firstvolume. For example, the expandable material 50 may be a particularmaterial (e.g., superabsorbent polymer) that absorbs a particular media(e.g., water, saline, etc.) and expands volumetrically in response tothat absorption. It is contemplated that a variety of differentexpandable materials and activating solutions may be utilized to achievethe volumetric expansion described above. Some examples of theexpandable materials and activating solutions and/or stimuli aredisclosed herein, however, other types of expandable materials andactivating solutions and/or stimuli are contemplated.

It can be appreciated that the sleeve 48 surrounding the expandablematerial 50 may need to be constructed from a material which is flexibleenough to expand in response to the expansion of the expandable material50 and, yet, strong enough to contain the expandable material 50 withoutrupturing. In other words, the sleeve 48 needs to be strong enough toprevent material from pre-maturely leaking prior to the desiredexpansion of the expandable material 50.

FIG. 7 illustrates one example methodology for activating (e.g.,contacting, engaging, etc.) the expandable material 50 by injecting aliquid through the sleeve 48 or piercing the sleeve 48 to permitsurrounding bodily fluid to contact the expandable material 50. FIG. 7shows a delivery catheter 56 having been advanced and positionedadjacent to the first end 16 of the stent 10. FIG. 7 further illustratesan injection needle 58 which has been extended through a lumen of thedelivery catheter 56 and advanced such that the distal end of the needle58 penetrates through the tubular framework 12, the covering 26, and thesleeve 48. After penetrating through the tubular framework 12, thecovering 26, and the sleeve 48, the distal end of the needle 58 may bein contact with the expandable material 50, whereby a liquid may beinjected through the needle such that the liquid contacts the expandablematerial 50. Alternatively, the needle 58, or penetrator, may beutilized to pierce the sleeve 48 to permit surrounding bodily fluid tocontact the expandable material 50. It is further contemplated that aneedle 58, a penetrator, (or similar device) may be inserted directlythrough the skin of a patient from a location adjacent the expandablemember 46.

It can be appreciated that the expandable member 46 may be designed suchthat other methods may be utilized to cause expansion of the expandablematerial 50. For example, the sleeve 48 may be constructed frombiodegradable and/or bioabsorbable material and the expandable member 46may be designed from material that expands upon contact with the bodilyfluids present within the body lumen 52. Accordingly, it can beappreciated that as the biodegradable material degrades, the expandablematerial 50 may be exposed to and expand in response to contact with thebodily fluids in the body lumen 52. Further, the biodegradable sleeve 48may be designed to biodegrade over a time period, thereby exposing theexpandable material to bodily fluids (e.g., blood, mucus, etc.) after apredetermined delay. It is further contemplated that biodegradationdescribed above may be trigger by a specific stimuli. For example, achange in the pH of an administered solution may be utilized to triggerthe biodegradation of the sleeve 48.

Additionally, it is contemplated that the sleeve 48 may be formed from aporous material. The porous material may be designed such that bodilyfluids may penetrate (e.g., diffuse, infiltrate, etc.) through thesleeve 48 at a rate dictated by the specific porosity of the materialused to construct the sleeve 48. In other words, the sleeve 48 may bedesigned to permit bodily fluid to pass therethrough, thereby permittingthe expandable material 50 to contact the bodily fluid at a given rateover a particular time period. Further, the expandable material 50 maybe designed to expand after a predetermined amount of fluid haspenetrated through the porous sleeve 48 and contacted the expandablematerial 50.

FIG. 8 illustrates another example stent 210. The stent 210 may besimilar in form and function similarly to other stents disclosed herein.For example, the stent 210 may include a tubular framework 212 having acovering 226 disposed thereon. Additionally, the stent 210 may include atissue ingrowth scaffold 228 positioned radially outward of the tubularframework 212 and covering 226. Further, an expansion cavity 240 may bedefined between the tissue ingrowth scaffold 228 and the tubularframework 212 (and covering 226). As shown in FIG. 8, an expandablemember 246 may be positioned within the expansion cavity 240. However,it is contemplated that the expandable member 246 may be inflatable. Inother words, as shown in FIG. 8, the expandable member 246 may includean inflatable sleeve 248 which defines an inflation chamber 268. Theinflation chamber 268 would be free of expandable material as describedabove with respect to stent 10, 110. However, the inflation chamber 268of stent 210 may be filled with a gel, a liquid, a gas or any otherfluid (or combinations thereof) which could be utilized to expand theinflatable sleeve 248.

FIG. 8 further illustrates a delivery catheter 56 having been advancedand positioned adjacent to the first end 216 of the stent 210. FIG. 8further illustrates an inflation device 258 which has been extendedthrough a lumen of the delivery catheter 56 and advanced such that thedistal end of the device 258 engages and/or penetrates the expandablesleeve 248. A variety of design configurations are contemplated toinject inflation media into the inflation chamber 268. For example, aneedle may be used to penetrate sleeve 248, whereby the inflation mediacould be inserted into the inflation chamber 268. Additionally, it iscontemplated that the sleeve 248 may include an inflation valve designedto couple with the distal end of the inflation device 258. Afterinjection of the inflation media, the inflation device 258 and deliverycatheter 56 may be retracted out of the patient.

FIG. 9 shows the stent 10 positioned in the body lumen 52 as describedabove. However, the detailed view of FIG. 9 further illustrates theexpansion of the expandable member 46 via the radially outward expansionof the expandable material 50. As described above, it can be appreciatedthat after the expandable material 50 has been activated, such asexposed to a stimuli, inflated, or contacted by a material (e.g.,liquid, etc.) that causes the volumetric expansion of the expandablematerial 50, the expandable material 50 may expand radially outward,axially or both radially outward and axially. In other words, theexpandable material 50 may expand from the tubular framework 12(including covering 26) toward the tissue grown into tissue ingrowthscaffold 28 (via the hyperplastic response, as described above).

In some instances the stent 10 may be configured to bias the directionin which the expandable member 46 expands. For example, the detailedview of FIG. 9 illustrates that stent 10 may be designed to bias theexpandable member 46 to expand radially outward (as shown by the arrowsin the detailed view of FIG. 9). It can be appreciated that in order tobias the expandable member 46 to expand radially outward (e.g., from thetubular framework 12 toward the tissue ingrowth scaffold 28), thetubular framework 12 may be designed to have a greater resistance toradially inward compression than the tissue ingrowth scaffold 28 has toradial outward expansion. In other words, as the expandable material 50radially expands, it may exert a uniform force in all directions,however, because the tubular framework 12 may be designed to have agreater resistance to inward compression than the tissue ingrowthscaffold 28 has to outward stretching, the expandable member 46 mayexpand in the direction of least resistance and, therefore, pushradially outward on the inner surface 44 of tissue ingrowth scaffold 28and any tissue ingrown into tissue ingrowth scaffold 28. Further, it canbe appreciated that as the expandable member 46 pushes against the innersurface 44 of the tissue ingrowth scaffold 28, it may push against thetissue 54 (not shown in FIG. 9, but shown in FIG. 6) which has growninto the tissue ingrowth scaffold 28 (via a hyperplastic response asdescribed above). This outward force exerted on the tissue by theexpandable member 46 may cause the tissue to recede back through theinterstices of the tissue ingrowth scaffold 28, thereby reducing tissuetrauma upon removal of the stent 10 and/or freeing the stent 10 from thebody lumen. It is contemplated that any of the examples of expandablemembers disclosed herein may function in a similar manner as thatdescribed above.

It can be appreciated that the amount of force generated by theexpandable member 46 may be proportional to the amount of expandablematerial 50 utilized in the design of stent 10. In other words, the moreexpandable material 50 that is positioned within the expandable member46 will generate a greater volumetric expansion and thus greaterradially outward force as compared to an equivalent stent design havinga lesser amount of expandable material 50. Similarly, it can beappreciated the tissue ingrowth scaffold 28 may be configured to limitthe amount of radial outward expansion generated by the expandablemember 46. For example, the tissue ingrowth member 28 may be designedsuch that it has a limited radial expansion. In other words, the tissueingrowth member 28 may be designed to expand up to a threshold diameter,at which point it will not expand any further. This threshold diametermay be correlated to a maximum expansion force generated by theexpandable member 46.

As described above, FIG. 9 illustrates stent 10 after the expandablemember 46 has been allowed to exert an outward radial force along theinner surface 44 of the tissue ingrowth scaffold 28 of the stent 10. Ascan appreciated from FIG. 9, the tissue 54 present in FIG. 6 haseffectively died off due to the outward radial force placed upon it bythe expandable member 46. Tissue death due to an outward radially forceplaced thereupon may be referred to as “pressure necrosis.” As discussedabove, because the expandable member 46 has reduced the amount of tissue54 extending through the tissue ingrowth scaffold 28, the tissue 54 nolonger attaches the stent 10 to the inner surface of body lumen 52 withas much force as when the tissue 54 is fully ingrown into the tissueingrowth scaffold 28. Accordingly, this reduced attachment forcetranslates into a lower force which is necessary to remove stent 10 fromthe body lumen 52, and thus less trauma to the body lumen 52.

FIG. 10 illustrates an example step in removing stent 10 from the bodylumen 52. Removal of the stent 10 may be performed once tissue that hasgrown into the tissue ingrowth scaffold 28 of the stent 10 hassufficiently receded. For example, removal of stent 10 may be performedapproximately 7-14 days after expansion of the expandable member 46. Insome instances, removal of stent 10 may be performed within 1 week orless, within 2 weeks or less, or within 3 weeks or less after expansionof the expandable member 46. Specifically, FIG. 10 illustrates that aclinician may utilize a retrieval device 66 (e.g., hook, forceps, etc.)to grasp or hook a retrieval suture 62 extending circumferentiallyaround the end of stent 10. When pulled proximally, the retrieval suture62 may collapse the first end 16 of stent 10 to facilitate withdrawal ofthe stent 10. The force exerted by the retrieval device 66 may besufficient to remove the stent 10 from the inner surface of the bodylumen 11 without damaging the inner surface of the body lumen 11.

FIGS. 11-14 illustrate another example stent 310. Stent 310 and FIGS.11-14 may be similar to the stent 10 and FIGS. 5-7 and 9. For example,FIG. 11 illustrates stent 310 including a tubular framework 312 having acovering 326 disposed along a portion thererof. Similarly to thatdescribed above, the covering 326 may prevent tissue from growingthrough the filaments 314 of the tubular framework 312 and into thelumen of the tubular framework 312. Further, FIG. 11 illustrates thatthe stent 310 may include a tissue ingrowth scaffold 328 similar to thetissue ingrowth scaffold 28 described above. Tissue ingrowth scaffold328 may be positioned radially outward of the tubular framework 312 andcovering 326, defining an expansion cavity therebetween. Additionally,the detailed view of FIG. 11 shows that the stent 310 may simply includean expandable material 350 that is disposed within the expansion cavitydefined between the tubular framework 312 and the tissue ingrowthscaffold 328. The expandable material 350 may include a superabsorbentmaterial (e.g., superabsorbent foam, superabsorbent beads, etc.). Insome examples, the superabsorbent material may be formed into smallbeads which are encapsulated in a magnetically responsive material, anelectroactive polymer, an ultrasound responsive material, or othersimilar material. When activated by a specific stimuli (e.g., magneticwaves, electromagnetic field, electroactive waves, ultrasound waves,etc.), the beads may break apart, thereby exposing the superabsorbentmaterial to surrounding bodily fluids. As discussed above, absorption ofthe fluid by the superabsorbent material may result in the expansion ofthe superabsorbent material. Further, in some examples the expandablematerial may be coupled to either the outer surface 342 of the tubularframework 312, the covering 326 and/or the inner surface 344 of thetissue ingrowth scaffold 328.

Similar to FIG. 6, FIG. 12 illustrates the stent 310 undergoing ahyperplastic response. For example, FIG. 12 illustrates tissue 54extending through the interstices of the filaments 330 along the tissueingrowth scaffold 328 of the stent 310. As discussed above, the tissueingrowth scaffold 328 (including the filaments 330) are uncovered, andtherefore, permit the radially inward growth of tissue through theinterstices of the tissue ingrowth scaffold 328. FIG. 12 furtherillustrates that the tissue 54 may grow into the tissue ingrowth region328 toward the expandable material 350 and the covering 326 (as depictedby the arrows in FIG. 12). It can be appreciated that the growth oftissue through the interstices of the tissue ingrowth scaffold 328 mayanchor the stent 310 along the body lumen 52, thereby limiting orpreventing the stent 310 from being dislodged due to peristaltic orother forces acting upon it.

FIG. 13 illustrates one example methodology to activate the expandablematerial 350 described above. FIG. 13 illustrates that in some examples,a source 366 (which may be positioned inside or outside of a patient'sbody) may be utilized to cause the expandable material 350 to expand. Insome examples, the source 366 may emit an activation “signal” 367 orstimuli which activates or stimulates the expandable material 350, asdescribed above. The signal 367 may include many different forms, someof which are described below.

For example, the source 366 may include an ultrasound device which isdesigned to emit ultrasound waves 367. The ultrasound waves 367 may passthrough a patient's body (including the body lumen 52), through thetissue ingrowth scaffold 328 and contact the expandable material 350.The expandable material 350 may be designed to expand in response to theultrasound waves 367.

In another example, the source 366 may emit magnetic waves. The magneticwaves 367 may pass through the patient's body (including the body lumen52), through the tissue ingrowth scaffold 328 and contact the expandablematerial 350. The expandable material 350 may be designed to expand inresponse to the magnetic waves.

In yet other examples, the source 366 may emit electroactive signals.The electroactive signals 367 may pass through the patient's body(including the body lumen 52), through the tissue ingrowth scaffold 328and contact the expandable material 350. The expandable material 350 mayinclude an electroactive polymer which is designed to expand in responseto the electroactive signals.

Additionally, it is contemplated that in some examples the source 366may be utilized to initiate the biodegradation of the sleeve 48described above with respect to stent 10. For example, a source 366positioned outside a patient's body may be used to initiate thebiodegradation of the sleeve 48 surrounding the expandable material 50.This may permit a clinician to precisely control the rate and timing inwhich the expandable material 50 may be exposed to bodily fluids whichmay cause its expansion (and, ultimately, the release of the stent 10from a body lumen).

Similar to FIG. 9, the detailed view of FIG. 14 illustrates the radiallyoutward expansion of the expandable material 350. As described abovewith respect to FIG. 9, it can be appreciated that after the expandablematerial 350 is activated by a stimulus that causes the volumetricexpansion of the expandable material 350, the expandable material 350may expand radially outward. In other words, FIG. 14 illustrates theexpandable material 350 may expand from the tubular framework 312(including covering 326) toward the tissue which has grown into tissueingrowth scaffold 328 (via a hyperplastic response, as described above).Similarly to FIG. 9, the detailed view of FIG. 14 illustrates that stent310 may be designed to bias the expandable material 350 to expandradially outward (as shown by the arrows in the detailed view of FIG.14) to exert a radially outward force on the tissue which has grown intothe tissue ingrowth scaffold 328, thereby reducing tissue trauma uponremoval of the stent 310 and/or releasing the stent 310 from the bodylumen as described above.

The materials that can be used for the various components of stent 10and stent 310 (and/or other stents disclosed herein) and the variousmedical devices disclosed herein may include those commonly associatedwith medical devices. For simplicity purposes, the following discussionmakes reference to stent 10 and stent 310 and other components of stent10 and stent 310. However, this is not intended to limit the devices andmethods described herein, as the discussion may be applied to othersimilar medical devices disclosed herein.

Stent 10, stent 110, stent 210 and stent 310 and other components ofstent 10, stent 110, stent 210 and stent 310 may be made from a metal,metal alloy, polymer (some examples of which are disclosed below), ametal-polymer composite, ceramics, combinations thereof, and the like,or other suitable material. Some examples of suitable polymers mayinclude polytetrafluoroethylene (PTFE), ethylene tetrafluoroethylene(ETFE), fluorinated ethylene propylene (FEP), polyoxymethylene (POM, forexample, DELRIN® available from DuPont), polyether block ester,polyurethane (for example, Polyurethane 85A), polypropylene (PP),polyvinylchloride (PVC), polyether-ester (for example, ARNITEL®available from DSM Engineering Plastics), ether or ester basedcopolymers (for example, butylene/poly(alkylene ether) phthalate and/orother polyester elastomers such as HYTREL® available from DuPont),polyamide (for example, DURETHAN® available from Bayer or CRISTAMID®available from Elf Atochem), elastomeric polyamides, blockpolyamide/ethers, polyether block amide (PEBA, for example availableunder the trade name PEBAX®), ethylene vinyl acetate copolymers (EVA),silicones, polyethylene (PE), Marlex high-density polyethylene, Marlexlow-density polyethylene, linear low density polyethylene (for exampleREXELL®), polyester, polybutylene terephthalate (PBT), polyethyleneterephthalate (PET), polytrimethylene terephthalate, polyethylenenaphthalate (PEN), polyetheretherketone (PEEK), polyimide (PI),polyetherimide (PEI), polyphenylene sulfide (PPS), polyphenylene oxide(PPO), poly paraphenylene terephthalamide (for example, KEVLAR®),polysulfone, nylon, nylon-12 (such as GRILAMID® available from EMSAmerican Grilon), perfluoro(propyl vinyl ether) (PFA), ethylene vinylalcohol, polyolefin, polystyrene, epoxy, polyvinylidene chloride (PVdC),poly(styrene-b-isobutylene-b-styrene) (for example, SIBS and/or SIBS50A), polycarbonates, ionomers, biocompatible polymers, other suitablematerials, or mixtures, combinations, copolymers thereof, polymer/metalcomposites, and the like. In some embodiments the sheath can be blendedwith a liquid crystal polymer (LCP). For example, the mixture cancontain up to about 6 percent LCP.

Some examples of suitable metals and metal alloys include stainlesssteel, such as 304V, 304L, and 316LV stainless steel; mild steel;nickel-titanium alloy such as linear-elastic and/or super-elasticnitinol; other nickel alloys such as nickel-chromium-molybdenum alloys(e.g., UNS: N06625 such as INCONEL® 625, UNS: N06022 such as HASTELLOY®C-22®, UNS: N10276 such as HASTELLOY® C276®, other HASTELLOY® alloys,and the like), nickel-copper alloys (e.g., UNS: N04400 such as MONEL®400, NICKELVAC® 400, NICORROS® 400, and the like),nickel-cobalt-chromium-molybdenum alloys (e.g., UNS: R30035 such asMP35-N® and the like), nickel-molybdenum alloys (e.g., UNS: N10665 suchas HASTELLOY® ALLOY B2®), other nickel-chromium alloys, othernickel-molybdenum alloys, other nickel-cobalt alloys, other nickel-ironalloys, other nickel-copper alloys, other nickel-tungsten or tungstenalloys, and the like; cobalt-chromium alloys; cobalt-chromium-molybdenumalloys (e.g., UNS: R30003 such as ELGILOY®, PHYNOX®, and the like);platinum enriched stainless steel; titanium; combinations thereof; andthe like; or any other suitable material.

In at least some embodiments, portions or all of stent 10, stent 110,stent 210 and stent 310 and other components of stent 10, stent 110,stent 210 and stent 310 may also be doped with, made of, or otherwiseinclude a radiopaque material. Radiopaque materials are understood to bematerials capable of producing a relatively bright image on afluoroscopy screen or another imaging technique during a medicalprocedure. This relatively bright image aids the user of stent 10, stent110, stent 210 and stent 310 in determining their locations. Someexamples of radiopaque materials can include, but are not limited to,gold, platinum, palladium, tantalum, tungsten alloy, polymer materialloaded with a radiopaque filler, and the like. Additionally, otherradiopaque marker bands and/or coils may also be incorporated into thedesign of stent 10, stent 110, stent 210 and stent 310 to achieve thesame result.

In some embodiments, a degree of Magnetic Resonance Imaging (MRI)compatibility is imparted into stent 10, stent 110, stent 210 and stent310. For example, stent 10, stent 110, stent 210 and stent 310 and othercomponents of stent 10, stent 110, stent 210 and stent 310, or portionsthereof, may be made of a material that does not substantially distortthe image and create substantial artifacts (e.g., gaps in the image).Stent 10, stent 110, stent 210 and stent 310 and other components ofstent 10, stent 110, stent 210 and stent 310 or portions thereof, mayalso be made from a material that the MRI machine can image. Somematerials that exhibit these characteristics include, for example,tungsten, cobalt-chromium-molybdenum alloys (e.g., UNS: R30003 such asELGILOY®, PHYNOX®, and the like), nickel-cobalt-chromium-molybdenumalloys (e.g., UNS: R30035 such as MP35-N® and the like), nitinol, andthe like, and others.

It should be understood that this disclosure is, in many respects, onlyillustrative. Changes may be made in details, particularly in matters ofshape, size, and arrangement of steps without exceeding the scope of thedisclosure. This may include, to the extent that it is appropriate, theuse of any of the features of one example embodiment being used in otherembodiments. The disclosure's scope is, of course, defined in thelanguage in which the appended claims are expressed.

What is claimed is:
 1. A stent, comprising: a tubular framework, thetubular framework including an inner surface, an outer surface and alumen extending therethrough; a tissue ingrowth scaffold extending alonga portion of the outer surface of the tubular framework, wherein thetissue ingrowth scaffold is spaced radially away from the outer surfaceof the tubular framework to define an expansion cavity therebetween, andwherein the tissue ingrowth scaffold permits tissue ingrowth along aportion thereof; and an expandable member positioned within at least aportion of the expansion cavity.
 2. The stent of claim 1, wherein theexpandable member is configured to expand radially outward toward aninner surface of the tissue ingrowth scaffold.
 3. The stent of claim 1,wherein the expandable member is configured to exert a radially outwardexpansion force on the tissue ingrowth scaffold such that the outersurface of the tissue ingrowth scaffold shifts radially outward from afirst positon to a second position.
 4. The stent of claim 1, wherein theexpandable member is configured to exert a radially outward force uponthe tissue ingrowth scaffold causing tissue ingrowth to recede.
 5. Thestent of claim 1, wherein the expandable member extendscircumferentially around the outer surface of the tubular framework. 6.The stent of claim 1, wherein the expandable member includes anexpandable sleeve and an expandable material positioned within a void ofthe expandable sleeve.
 7. The stent of claim 6, wherein the expandablematerial is configured to expand when exposed to an external stimuli. 8.The stent of claim 7, wherein the external stimuli is a liquid.
 9. Thestent of claim 6, wherein the expandable sleeve is configured todissolve over a time period to expose the expandable material.
 10. Thestent of claim 1, wherein the expandable member includes an inflatablesleeve, and wherein the inflatable sleeve is configured to shift from afirst unexpanded configuration to a second expanded configuration wheninflated.
 11. The stent of claim 1, wherein the tissue ingrowth scaffoldextends along the outer surface of the tubular framework from an end ofthe tubular framework, and wherein the scaffold folds back on thetubular framework to form the expansion cavity.
 12. The stent of claim1, further comprising a covering disposed along a portion of the tubularframework, wherein the covering is configured to prevent tissue fromgrowing into the lumen of the tubular framework.
 13. The stent of claim1, wherein the tissue ingrowth scaffold includes a wire mesh having oneor more apertures configured to permit tissue ingrowth therethrough. 14.A stent, comprising: a tubular framework having a first end and a secondend opposite the first end, the tubular framework including an innersurface, an outer surface and a lumen extending therethrough; a tissueingrowth scaffold extending along a portion of the outer surface of thetubular framework, wherein the tissue ingrowth scaffold is spacedradially away from the outer surface of the tubular framework to definean expansion cavity therebetween, and wherein the tissue ingrowthscaffold permits tissue ingrowth along a portion thereof; a coveringdisposed along the tubular framework, wherein the covering is configuredto prevent tissue from growing into the lumen of the tubular frameworkbetween the first end and the second end; and an expandable memberpositioned within at least a portion of the expansion cavity, theexpandable member configured to radially expand from a first nominalstate to an expanded state when subjected to an external stimuli,wherein the expandable member is configured to exert a radially outwardforce upon the tissue ingrowth scaffold in the expanded state to causetissue ingrowth within the tissue ingrowth scaffold to recede.
 15. Thestent of claim 14, wherein the expandable member is configured to expandradially outward toward an inner surface of the tissue ingrowthscaffold.
 16. The stent of claim 14, wherein the expandable memberextends circumferentially around the outer surface of the tubularframework.
 17. The stent of claim 14, wherein the expandable memberincludes an expandable sleeve and an expandable material positionedwithin a void of the expandable sleeve.
 18. The stent of claim 17,wherein the external stimuli is a liquid.
 19. The stent of claim 14,wherein the tissue ingrowth scaffold includes a wire mesh having one ormore apertures configured to permit tissue ingrowth therethrough.
 20. Amethod of treating a body lumen, the method comprising: activating anexpandable member positioned between a tissue ingrowth scaffold and atubular framework of a pre-deployed stent having tissue ingrown into thetissue ingrowth scaffold; wherein activating the expandable membercauses the expandable member to shift radially from a first unexpandedconfiguration to a second expanded configuration; wherein shifting theexpandable member from a first unexpanded configuration to a secondexpanded configuration includes exerting a radially outward force uponthe tissue which has grown into the tissue ingrowth scaffold; andwherein exerting a radially outward force upon the tissue which hasgrown into the tissue ingrowth scaffold causes the tissue to recede.